Do they make a wall mount for the new iMac?
No, possibly in the future.
At the moment, there aren't any wall adapters for the Late 2012 iMac. See > http://support.apple.com/kb/HT5619
I did see one company that might do what you're looking for. You don't say what size iMac you have....
But...take a look at this link:
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